Fisher S H, Wray L V
Department of Microbiology, Boston University School of Medicine, Massachusetts 02118.
J Bacteriol. 1989 May;171(5):2378-83. doi: 10.1128/jb.171.5.2378-2383.1989.
Glutamine synthetase (GS) in Streptomyces coelicolor was shown to be regulated at two levels. First, the S. coelicolor GS protein is subject to a posttranslational covalent modification which is likely to involve adenylylation. Adenylylation is important in regulating GS activity both after sudden changes in ammonium availability and during steady-state growth. Since higher levels of adenylylated GS were seen in S. coelicolor mutants deficient in glutamate synthase than in wild-type cells, glutamine or a metabolite derived from glutamine is likely to be involved in the metabolic signal that regulates GS adenylylation. Second, the GS structural gene (glnA) is transcriptionally regulated in response to nitrogen availability during steady-state growth. Transcription of the glnA gene occurred from the same promoter during vegetative growth, stationary phase, and sporulation. The nucleotide sequence of this promoter has significant homology with the -10, but not the -35, region of the consensus sequence of Streptomyces vegetative promoters. The glnA gene is transcribed as a monocistronic mRNA.
天蓝色链霉菌中的谷氨酰胺合成酶（GS）在两个水平上受到调控。首先，天蓝色链霉菌GS蛋白会经历翻译后共价修饰，这可能涉及腺苷酸化。腺苷酸化在铵供应突然变化后以及稳态生长期间对调节GS活性都很重要。由于在谷氨酸合酶缺陷的天蓝色链霉菌突变体中观察到的腺苷酸化GS水平高于野生型细胞，谷氨酰胺或源自谷氨酰胺的代谢物可能参与调节GS腺苷酸化的代谢信号。其次，GS结构基因（glnA）在稳态生长期间响应氮供应进行转录调控。在营养生长、稳定期和孢子形成期间，glnA基因从相同的启动子转录。该启动子的核苷酸序列与链霉菌营养启动子共有序列的 -10 区域具有显著同源性，但与 -35 区域没有同源性。glnA基因转录为单顺反子mRNA。
